Stoking devices for fire grates



June 19, 1956 K. RADERMACHER 2,751,060

swoxmc; DEVICES FOR FIRE GRATES Filed Aug. 18, 1952 2 Sheets-Sheet 1 *"i "-F EQTAIH Inveman' .-w,,,zz1\; 404 M w 4TTOR NE ys June 19, 1956 K. RADERMACHER 2,751,060

STOKING DEVICES FOR FIRE GRATES Filed Aug. 18, 1952 2 Sheets-Sheet 2 Inventor:

United States Patent STOKING DEVICES FOR FIRE GRATES Karl Radermacher, Gummersbach-Strombach, Germany,

assignor to L. & C. Steinmuller G. m. b. H., Gummersbach, Rhineland, Germany Application August 18, 1952, Serial No. 304,837

Claims priority, application Germany September 18, 1951 7 Claims. (Cl. 198-56) This invention relates to a fuel stoking device for fire grates for ensuring an even distribution of the fuel over the Whole width of the grate.

It is a well known practice to use as a device for stoking the fuel for fire grates oscillating shakers, vibrating chutes, distributing carriages with and without cells, travelling to and fro above the grate hopper, travelling belts and the like, for instance in combination with distributing devices. The disadvantages of these arrangements consist in this, that a definite minimum inclination must be adhered to or an easily damaged electrical or complicated mechanical control arrangement has to be provided, so that in most cases particularly strict attention and servicing or the provision of signalling devices, liable to getting out of order, are required.

According to the invention these disadvantages are avoided, without the evenness of the coal distribution suffering in any way.

The invention consists in this, that leading from a hopper or the like, preferably disposed in the middle of the grate trough, there is mounted a distributing worm provided with left-hand or right-hand convolutions. This worm is fixed in a tubular member which is closed at both ends and rotates with it, the tubular member having a slot extending along its entire length in the axial direction, which slot serves the purpose of an inlet and outlet opening for the fuel. By turning the enclosed distributing worm, the fuel coming from the fixed hopper passes through the slot in the tubular member from above to the start of the distributing worm, from where, corresponding to the speed of revolution and pitch of the distributing worm, it is conveyed to the sides and, in so far as empty space is created by the forward feed of the grate, falls through the slot downwards into the grate trough.

A special advantage of the invention consists in this, that, even when the grate trough is full, the distributing worm can continue to rotate, as there can be no accumulation of fuel, so that any alteration in the speed of revolution is unnecessary, when the distributing worm is rotated at the speed corresponding to the maximum fuel requirement.

It is frequently required to charge fire grates with relatively moist fuels which have the tendency to adhere to the walls of the stoking device, which may lead to trouble. This adhesion of the fuel may be prevented through the distributing Worm or the tubular member enclosing it or both parts being heated by any suitable heating medium (for instance waste steam, hot air, flue gas and the like). In that case the distributing Worm will preferably be made hollow and the tubular member formed by two tubes lying one in the other, so that the heating medium can be conveyed through the remaining hollow space, in which case ribs may be provided inside the hollow spaces.

In a further modification of the invention the slot in the distributing worm casing is made helical, providing the advantage, that the resistance to the rotation of the disice tributing worm will be only very slight, owing to the helical motion in the fuel charge of the grate trough.

It has been found, that a separation of the fuel in the cross section of the fixed feed hopper may cause one side of the worm and consequently of the grate to be fed to a greater extent with coarsely granulated and the other side mainly with more finely granulated fuel. This disadvantage may be overcome by the expedient, that, according to a further modification of the invention, the rotating tube containing the distributing worm is divided into two independent halves by a partition extending obliquely across the width of the hopper, the inlet and outlet slots of the two tube halves being ofiset with respect to one another by so that, onthe tube rotating, alternately the right-hand or the left-hand half .is charged with fuel out of the entire cross-section of the hopper.

As the fuels accumulating while falling frequently contain coarsish pieces, more particularly when delivered unsorted, there is the danger that these pieces may block the feeding device at the entrance to the worm. To overcome this drawback, according to a further feature of the invention there is mounted in the hopper immediately above the rotating tubular member with the distributing worm a flap which under its own weight, through being spring loaded or otherwise normally keeps the opening in the hopper wall tightly closed, but at the moment, in which coarser fuel lumps arrive and cannot be coped with by the distributing worm, opens by yielding to the pressure and allows the coarse lump to fall alongside the hopper into the grate trough, whereupon it closes again.

These expedients have already proved useful in practice and act as a good safety device for the arrangement.

The invention is illustrated by Way of example in the accompanying drawings, in which:

Figure 1 shows a portion of a travelling grate viewed from the front and Figure 2 a section on line AA of Figure 1.

Figure 3 shows a portion of a fuel stoking device in the region of the feeding place in vertical longitudinal section and Figure 4 a section on line AA of Figure 3.

The fuel is fed through the fixed hopper 1 into the grate trough 2, in the upper part of which is disposed the distributing worm 45 which is encased in the rotating tubular member 3 and is driven with the latter by way of gearing 6. The hopper 1 delivers on to distributing worm 45 rotating with the tubular member 3, the worm being divided up at this place into a left-handed part 4 and a right-handed part 5. The tubular member 3 has a slot 7 of about Ms of the tube circumference, which extends helically along its entire length and through which in the region of the hopper 1 the fuel reaches the worm and is thus conveyed, until, when the slot 7 at the bottom and the grate trough 2 is free, it can fall out. Fuel slipping out of the hopper 1 passes, when the position is that according to Figure 3, through the slot 7a into the left-hand half 3a of the tubular member 3 with the distributing worm 4, whilst at the same time the fuel in the right-hand half 3b of the tubular member 3 passes through the slot 7b into the grate trough. At each revolution of the tubular member through 180 the mode of operation is the same, that is to say the fuel passes alternately through the left-hand or the right-hand half of the distributor into the grate trough. The partition 8 fitted obliquely in the tubular member 3 and dividing the worm 4-5 ensures this alternate charging.

The point where the hopper delivers into the grate trough and thereby into the distributing arrangement may in certain circumstances be positioned laterally of the grate centre, so that tube sections of different length are formed. In this case the positioning of the slots in the 3 tube sections must be made to correspond to the division ratio.

In the lower part of the fixed hopper 1 a weight-loaded flap 9 is provided, which, on the occurrence of coarse lumps, which are not caught by the distributing worm, opens by yielding to the pressure and allows the coarse fuel to fall into the grate trough 2, by-passing the distributing worm 45.

I claim:

1. A distributing device comprising a fixed charging hopper, a distributing worm mounted beneath said hopper, a tubular member encasing said worm, said tubular member being closed at both ends and having a slot extending along its entire length and affording communication between said hopper and said worm, and means for rotating the worm at the tubular member together at the same angular velocity.

2. A device as claimed in claim 1, in which the distributing worm has left-hand and right-hand convolutions which start in the region of the charging hopper.

3. A device as claimed in claim 1, in which the dis tributing worm is hollow.

4. A device as claimed in claim 1, in which the slot in the tubular member encasing the worm is helical.

5. A device as claimed in claim 1, in which the tubular member has a partition extending obliquely thereacross in the region of communication between said hopper and said worm.

6. A distributing device comprising a fixed charging hopper, a distributing worm mounted beneath said hopper, a tubular member encasing said worm, said tubular member being closed at both ends, transverse. partition means dividing the tubular member into two sections each section having a slot, the two slots being angularly offset with respect to one another, and means for rotating the worm and tubular member together at the same angular velocity. I

7. A device as claimed in claim 1, including a flap at the lower end of the hopper and means loading the flap.

References Cited in the file of this patent UNITED STATES PATENTS 506,172 Fulwider Oct. 3, 1893 803,777 McConnell Nov. 7, 1905 1,716,071 MacArthur June 4, 1929 2,332,688 Baily Oct. 26, 1943 2,630,906 Philipp Mar. 10, 1953 

